Carbono nas frações humificadas da matéria orgânica do solo após dois anos de rotação de cultura.
Caetano Alves de Lima Neto
Universidade Federal Rural do Semi-Árido
Andler Milton de Paiva Oliveira
Eulene Francisco da Silva
Paulo Ricardo Chagas oliveira
Francisco Éder Rodrigues de Oliveira
Palavras-chave: Humina, ácido húmico, ácido fúlvico, milho
Resumo
The carbon in the humified fractions of organic matter plays an essential role in structural stability, fertility, and soil resilience, and is a key indicator for assessing the effects of agricultural management in semiarid regions. This study evaluated the carbon of humic substances (CHS), humin (CHUM), humic acid (CHA), and fulvic acid (CFA) in a sandy Latosol of the semiarid Northeast region after two years of crop successions (melon, corn, and cowpea), compared to soils under native Caatinga forest. Samples were collected from the 0–10 and 10–20 cm layers and subjected to chemical analysis by differential solubility, with statistical evaluation via ANOVA-RT. A significant interaction between crop succession and depth was observed (p<0.01), with higher humified carbon contents in the native forest. Reductions in cultivated areas were significant, reaching up to –92% in CHA under melon at the surface. Corn stood out among the agricultural successions, maintaining CHA values similar to those of the forest at 0–10 cm, due to its high biomass input and the rhizodeposition typical of C4 grasses, favoring both the accumulation of labile carbon and the formation of stable compounds. In contrast, melon and cowpea showed more intense losses, confirming their lower efficiency in preserving organic matter.